import { Injectable } from '@nestjs/common';
import { and, desc, eq } from 'drizzle-orm';
import { db } from '../db/client';
import { observations } from '../db/schema';
import { AuditService } from '../audit/audit.service';
import type { AuthenticatedSession } from '../auth/tenant.guard';
import type { CreateObservationDto } from './dto';

@Injectable()
export class ObservationsService {
  constructor(private readonly audit: AuditService) {}

  async list(session: AuthenticatedSession, subjectType?: string, subjectId?: string) {
    return db.query.observations.findMany({
      where: and(
        eq(observations.tenantId, session.tenantId),
        ...(subjectType ? [eq(observations.subjectType, subjectType)] : []),
        ...(subjectId ? [eq(observations.subjectId, subjectId)] : []),
      ),
      orderBy: desc(observations.observedAt),
    });
  }

  async create(session: AuthenticatedSession, dto: CreateObservationDto) {
    const [row] = await db
      .insert(observations)
      .values({
        tenantId: session.tenantId,
        subjectType: dto.subjectType,
        subjectId: dto.subjectId,
        metric: dto.metric,
        value: dto.value,
        unit: dto.unit,
        source: dto.source,
        observedAt: dto.observedAt ? new Date(dto.observedAt) : new Date(),
        confidence: dto.confidence !== undefined ? String(dto.confidence) : undefined,
      })
      .returning();
    await this.audit.record(null, {
      tenantId: session.tenantId,
      actorId: session.userId,
      action: 'observation.created',
      resource: `observation:${row.id}:${dto.subjectType}/${dto.subjectId}`,
    });
    return row;
  }
}